The present invention relates to a rotational angle signal generating system for an internal combustion engine, which is to be used with a controller for controlling the fuel injection timing or the ignition timing of the engine in association with the r.p.m., the water temperature or the like thereof.
As a control means for the ignition system of an internal combustion engine of an automobile or the like, there has been used in recent years a method by which the running mode of the engine is detected by means of a variety of sensors so that the engine may be centrally controlled by a micro-computer in accordance with the detected signals.
As the data for discriminating the running mode of the engine, there may be listed the r.p.m., the crank angle, the manifold vacuum or the water temperature of the engine. As the sensors, on the other hand, there have been developed sensors used exclusively for detecting the above data. Of these sensors, there has been developed a crank angle detector for generating an engine rotational angle signal by combining a plurality of projections, which are formed at predetermined anglular spacings on a rotary disc having a large diameter connected directly to a crankshaft, with a magnetic pickup.
Typical examples of such systems include the devices disclosed by U.S. Pat. Nos. 4,054,111 to Sand; 4,036,190 to Bigliani and 3,903,857 to Honing. In the Honing and Sand Patents, an element is secured to the crankshaft and is provided with angular indicia of various types detected by a sensor or sensors associated therewith. In Bigliani, a pair of pick-ups are used to detect a pair of indicia (teeth and a "protuberance") provided on the flywheel.
However, the existing rotational angle signal generating systems using such crank angle sensors and etc. have a defect in that they are difficult to adjust, and it is required to use a separate distributor for distributing a high voltage to the ignition plugs because the aforementioned crank angle sensor is mounted on the crankshaft.